This invention relates to a thermometer.
One popular form of thermometer includes a bimetallic sensing element disposed in a metal tube which allows the sensing element to be placed in an environment in which temperature sensing is desired. A dial case mounted at one end of the tube contains a scale. A pointer coupled to the sensing element traverses the scale to provide an indication of temperature sensed by the sensing element.
The angular position of the dial case relative to the tube can be adjusted in order to change the relative positions of the indicator and the scale and thereby calibrate the thermometer. A spring biased friction engagement secures the dial case and the metal tube in their adjusted relative positions. The slip joint that permits relative rotation between the tube and the dial case is relatively tight to prevent the entrance of contaminants and the dial case is relatively small for portability and convenience. Consequently, it is difficult for the user to calibrate the thermometer in the field without having access to suitable tools.